Electric working machine

ABSTRACT

An electric working machine in one aspect of the present disclosure includes: a motor; a driver to drive the motor; a first control circuit; and a second control circuit. The first control circuit controls the driver such that the motor rotates in a set rotation direction. The second control circuit is provided separately from the first control circuit. The second control circuit detects a rotation direction of the motor and performs an abnormality handling process to stop rotation of the motor in response to a situation where the detected rotation direction is reverse to the set rotation direction.

CROSS-REFERENCE TO RELATED APPLICATION

This international application claims the benefit of Japanese PatentApplication No. 2016-228009 filed on Nov. 24, 2016 with the Japan PatentOffice, and the entire disclosure of Japanese Patent Application No.2016-228009 is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a technique to control a motor in anelectric working machine.

BACKGROUND ART

In an electric power tool disclosed in Patent Document 1 below, acontrol circuit determines a rotation direction of a motor based on asignal inputted from a forward-reverse switch that is operated by auser, and rotates the motor based on a detection signal from a Hallelement to detect a rotor position.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: Japanese Unexamined Patent Application PublicationNo. 2013-188825

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

In the above-described electric power tool, if an abnormality occurs inthe control circuit, thereby disabling normal control of the motor, themotor might rotate in a reverse direction to a set rotation direction.

If the motor rotates in the reverse direction to the set rotationdirection, processing unintended by the user might be performed, orvarious influences might be caused on the user or the electric workingmachine itself.

In one aspect of the present disclosure, it is preferable to enablereduction in various influences that might be caused by rotation of amotor of an electric working machine in a reverse direction to a setrotation direction.

Means for Solving the Problems

An electric working machine in one aspect of the present disclosureincludes: a motor; a driver; a first control circuit; and a secondcontrol circuit. The driver drives the motor by electric power suppliedfrom a power source. The first control circuit controls the driver suchthat the motor rotates in a set rotation direction. The second controlcircuit is provided separately from the first control circuit. Thesecond control circuit detects a rotation direction of the motor, andthe second control circuit executes an abnormality handling process tostop rotation of the motor in response to a situation where the detectedrotation direction is reverse to the set rotation direction.

In the electric working machine configured as described above, thesecond control circuit provided separately from the first controlcircuit monitors the rotation direction of the motor. The second controlcircuit executes the abnormality handling process if the motor rotatesin the reverse direction. Thus, various influences that might be causedby the rotation of the motor in the reverse direction can be reduced.

The abnormality handling process may include any process. For example,the abnormality handling process may include a notification process ofproviding a specific notification to the first control circuit. Then,the first control circuit may stop rotation of the motor through thedriver in response to execution of the notification process.

In this case, the motor can be stopped by a simple process that thesecond control circuit provides the specific notification to the firstcontrol circuit in response to a rotation of the motor in the reversedirection.

The electric working machine may further include at least one specifiedelectric wiring and an interrupter. The at least one specified electricwiring is configured to be such that interruption of the at least onespecified electric wiring during rotation of the motor by the drivercauses the motor to stop rotation. The interrupter is provided to the atleast one specified electric wiring and configured capable ofinterrupting the at least one specified electric wiring. Also, theabnormality handling process may include a process of interrupting theat least one specified electric wiring by the interrupter.

In this case, the motor can be stopped by a simple process ofinterrupting the at least one specified electric wiring in response to arotation of the motor in the reverse direction.

The at least one specified electric wiring may include a drive wiring tosupply electric power from the power source to the driver, and thedriver may be configured to drive the motor by the electric powersupplied from the power source through the drive wiring.

In this case, the motor can be stopped by a simple process ofinterrupting the drive wiring in response to a rotation of the motor inthe reverse direction.

The at least one specified electric wiring may include a control wiringto output a control signal from the first control circuit to the driver,and the driver may be configured to drive the motor in accordance withthe control signal inputted from the first control circuit through thecontrol wiring.

In this case, the motor can be stopped by a simple process ofinterrupting the control wiring in response to a rotation of the motorin the reverse direction.

The electric working machine may further include a power supplierconfigured to generate a power-supply electric power to operate thefirst control circuit. The at least one specified electric wiring mayinclude a power supply wiring to supply the power-supply electric powergenerated by the power supplier to the first control circuit. The firstcontrol circuit may be configured to operate by the power-supplyelectric power inputted from the power supplier through the power supplywiring, to thereby control the driver.

In this case, the motor can be stopped by a simple process ofinterrupting the power supply wiring in response to a rotation of themotor in the reverse direction.

The electric working machine may further include a position informationoutputter configured to output rotational position informationindicating a rotational position of the motor. The first control circuitmay be configured to control the driver based on the rotational positioninformation outputted from the position information outputter, tothereby rotate the motor in the set rotation direction. Also, the secondcontrol circuit may be configured to detect the rotation direction ofthe motor based on the rotational position information outputted fromthe position information outputter.

In this case, the rotational position information outputted from theposition information outputter is shared by the first control circuitand the second control circuit. Accordingly, a simplified configurationof the electric working machine can be achieved, as compared with a casewhere, for example, the second control circuit detects the rotationdirection based on information that is independent from the rotationalposition information from the position information outputter.

The electric working machine may include a first controller includingthe first control circuit and a second controller including the secondcontrol circuit. The rotational position information outputted from theposition information outputter may be inputted to the second controller.The second controller may be configured to output the rotationalposition information inputted from the position information outputter tothe first controller. The first control circuit may be configured tocontrol the driver based on the rotational position information inputtedfrom the second controller, and the first control circuit may beconfigured to stop driving of the motor by the driver in response tostopping of input of the rotational position information from the secondcontroller. Also, the abnormality handling process may include a processof stopping output of the rotational position information from thesecond controller to the first controller.

In this case, the motor can be stopped by a simple process of stoppingoutput of the rotational position information from the second controllerto the first controller in response to a rotation of the motor in thereverse direction.

The electric working machine may further include a direction selectingoperation device configured to be operated to set the rotation directionof the motor to a first direction or a second direction. The setrotation direction may correspond to the rotation direction set by thedirection selecting operation device.

In this case, the motor can be stopped by the abnormality handlingprocess in response to a rotation of the motor in the reverse direction,regardless of which of the first direction and the second direction theset rotation direction is.

The electric working machine may further include an instructionoperation device configured to be operated by an operator of theelectric working machine to rotate the motor. The first control circuitand the second control circuit may be configured to operate in responseto an operation of the instruction operation device.

In such electric working machine, monitoring of the rotation directionand a process based on results of the monitoring by the second controlcircuit are performed while rotation of the motor is instructed by theinstruction operation device, and are not performed while stopping ofthe motor is instructed. Accordingly, as compared with a case where thesecond control circuit constantly operates to monitor the rotationdirection, power consumption required for operation of the secondcontrol circuit can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an electric working machine of afirst embodiment.

FIG. 2 is a configuration diagram showing an electrical configuration ofthe electric working machine of the first embodiment.

FIG. 3 is a flowchart showing a motor control process of the firstembodiment.

FIG. 4 is a flowchart showing an abnormality monitoring process of thefirst embodiment.

FIG. 5 is a configuration diagram showing an electrical configuration ofan electric working machine of a second embodiment.

FIG. 6 is a configuration diagram showing an electrical configuration ofan electric working machine of a third embodiment.

FIG. 7 is a configuration diagram showing an electrical configuration ofan electric working machine of a fourth embodiment.

FIG. 8 is a flowchart showing a motor control process of the fourthembodiment.

EXPLANATION OF REFERENCE NUMERALS

1, 70, 80, 100 . . . electric working machine; 9 . . . trigger operationportion; 10 . . . battery pack; 11 . . . first contact; 12 . . . secondcontact; 13 . . . trigger switch; 15 . . . battery; 20, 71, 81, 101 . .. first controller; 21, 72, 102 . . . first control circuit; 21 a, 51 a. . . CPU; 21 b, 51 b . . . memory; 22 . . . power supply controller; 23. . . switch signal detector; 24 . . . current detector; 25 . . .battery voltage detector; 26 . . . board temperature detector; 27 . . .FET temperature detector; 30 . . . drive circuit; 40 . . . motor unit;41 . . . motor; 42, 83 . . . rotor position detector; 46 . . . firstsignal line; 47 . . . second signal line; 48 . . . third signal line;50, 75, 85, 110 . . . second controller; 51, 76, 86, 111 . . . secondcontrol circuit; 52 . . . first interrupter; 53 . . . secondinterrupter; 54 . . . third interrupter; 73 . . . forward/reverseselector switch; 103 . . . control power supply interrupter; 104 . . .gate signal interrupter; 105 . . . drive power supply interrupter; 113 .. . power supply wiring; 114 . . . gate signal wiring; 115 . . . drivewiring; Q1 to Q6 . . . semiconductor switching element.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, example embodiments of the present disclosure will bedescribed with reference to the drawings.

1. First Embodiment

(1-1) Overall Configuration of Electric Working Machine 1

As shown in FIG. 1 , an electric working machine 1 of the presentembodiment is configured as a circular saw to be used mainly for cuttinga workpiece. The electric working machine 1 includes a base 2 and a mainbody 3. The base 2 is a substantially rectangular member that is broughtinto abutment with an upper surface of a workpiece to be cut during acutting operation of the workpiece using the electric working machine 1.The main body 3 is arranged on an upper surface side of the base 2.

The main body 3 includes a circular saw blade 4, a saw blade case 5, anda cover 6. The saw blade 4 is arranged on a right side of the main body3 in a forward cutting direction. The saw blade case 5 is provided tohouse and cover a peripheral edge of substantially an upper semicirculararea of the saw blade 4.

The cover 6 is provided to cover a peripheral edge of substantially alower semicircular area of the saw blade 4. The cover 6 is openable andclosable, and FIG. 1 shows a state where the cover 6 is closed. Bymoving the electric working machine 1 in the forward cutting directionduring cutting of the workpiece, the cover 6 pivots about a rotationcenter of the saw blade 4 in a counter-clockwise direction in the figureand is gradually opened. Accordingly, the saw blade 4 is exposed, andits exposed part is made to cut into the workpiece.

A substantially cylindrical motor case 7 is provided on a left side ofthe main body 3. The motor case 7 houses a motor 41. The motor 41 is adrive source of the electric working machine 1. A not-shown gearmechanism is housed between the motor case 7 and the saw blade 4. Whenthe motor 41 rotates, the rotation is transmitted through the gearmechanism to the saw blade 4, and the saw blade 4 rotates.

A handle 8 to be gripped by a user of the electric working machine 1 isprovided on an upper side of the main body 3. The handle 8 is mounted inan arch shape on the upper side of the main body 3. Specifically, afirst end of the handle 8 is fixed to a rear end of the main body 3along the forward cutting direction, and a second end of the handle 8 isfixed to a forward part of the main body 3 along the forward cuttingdirection relative to the first end of the handle 8.

A trigger operation portion 9 is provided to the handle 8. The user ofthe electric working machine 1 can perform a pull operation and arelease operation of the trigger operation portion 9 while gripping thehandle 8. By pressing a not-shown lock button while the triggeroperation portion 9 is in a pull-operated state, the trigger operationportion 9 can be locked in the pull-operated state.

At the rear end of the main body 3, a battery pack 10 housing arepeatedly rechargeable battery 15 is detachably attached. It isconfigured such that when the trigger operation portion 9 ispull-operated while the battery pack 10 is attached to the main body 3,the motor 41 in the main body 3 rotates by electric power of the battery15.

(1-2) Electrical Configuration of Electric Working Machine 1

A description will be given of an electrical configuration of theelectric working machine 1 using FIG. 2 . As shown in FIG. 2 , theelectric working machine 1 includes a motor unit 40, a first controller20, a second controller 50, and a trigger switch 13. Also, the electricworking machine 1 includes the battery pack 10, which is also shown inFIG. 1 . FIG. 1 shows a state where the battery pack 10 is attached tothe main body 3.

The battery pack 10 houses the battery 15. The battery 15 of the presentembodiment is, for example, a lithium ion rechargeable battery. However,the battery 15 may be a rechargeable battery other than a lithium ionrechargeable battery. The battery 15 can be charged by detaching thebattery pack 10 from the electric working machine 1 and attaching thesame to a not-shown charger.

The battery pack 10 is configured to be able to output battery stateinformation indicating a state of the battery 15. The battery pack 10may include, for example, a monitoring module for the battery 15. Themonitoring module may be configured to detect abnormalities of thebattery 15 and to output the detected abnormalities as the battery stateinformation. Abnormalities of the battery 15 may include, for example,overcurrent, overdischarge, and overheat.

Also, for example, the battery pack 10 may be configured to detectphysical quantities indicating a state of the battery 15, and to outputinformation indicating the detected physical quantities as battery stateinformation. The physical quantities indicating the state of the battery15 may include, for example, a voltage value of the battery 15, voltagevalues of respective battery cells included in the battery 15, a valueof current discharged from the battery 15, and a temperature of thebattery 15.

The trigger switch 13 includes two contacts, which are a first contact11 and a second contact 12. The trigger switch 13 is turned ON and OFFin an interlocked manner with the trigger operation portion 9 shown inFIG. 1 . Specifically, when the trigger operation portion 9 ispull-operated, the trigger switch 13 is turned ON, that is, both of thefirst contact 11 and the second contact 12 are turned ON, and both ofthe first contact 11 and the second contact 12 are closed. On the otherhand, in a state where the trigger operation portion 9 is notpull-operated, the trigger switch 13 is OFF, that is, both of the firstcontact 11 and the second contact 12 are OFF, and both of the firstcontact 11 and the second contact 12 are opened.

A first end of the first contact 11 and a first end of the secondcontact 12 are both coupled to a positive electrode of the battery 15. Asecond end of the first contact 11 and a second end of the secondcontact 12 are both coupled to the first controller 20.

The motor unit 40 includes the motor 41 and a rotor position detector42. In the present embodiment, the motor 41 is a brushless motorconfigured to be driven by receiving supply of three-phase power.

The rotor position detector 42 is configured to output a signal inaccordance with a rotational position of a rotor of the motor 41. In thedescription hereinafter, a rotational position with respect to the motor41 specifically means a rotational position of the rotor.

The rotor position detector 42 includes three Hall sensors. The Hallsensors are arranged mutually spaced apart by an electrical angle of 120degrees around the rotor of the motor 41. The three Hall sensors outputrespective first position signal, second position signal, and thirdposition signal. These three position signals are signals each accordingto a relative positional relationship between a corresponding one of theHall sensors and the rotor of the motor 41. The Hall sensors eachinclude a Hall element and a signal process circuit that processes andconverts an output signal from the Hall element into a binary digitalsignal. The binary digital signal is outputted as the position signal.

The first position signal to the third position signal outputted fromthe rotor position detector 42 are inputted to a first control circuit21 in the first controller 20. More specifically, the first positionsignal is inputted to the first control circuit 21 through a firstsignal line 46, the second position signal is inputted to the firstcontrol circuit 21 through a second signal line 47, and the thirdposition signal is inputted to the first control circuit 21 through athird signal line 48.

The three signal lines 46 to 48 pass through the second controller 50between the motor unit 40 and the first controller 20. That is, theposition signals outputted from the Hall sensors of the rotor positiondetector 42 are inputted to the first control circuit 21 through thesecond controller 50.

A control power supply voltage is inputted to the rotor positiondetector 42 from the first controller 20. Each of the Hall sensors inthe rotor position detector 42 operates by using the control powersupply voltage inputted from the first controller 20 as the powersupply. Also, a ground terminal of each of the Hall sensors is coupledto the ground line that has an equal potential to a negative electrodeof the battery 15.

In the present embodiment, the supply of a control power supply voltagefrom the first controller 20 to the rotor position detector 42, andcoupling between the rotor position detector 42 and the ground line areconfigured to be through the second controller 50; however, these neednot be performed through the second controller 50. For example, thecontrol power supply voltage may be supplied from the first controller20 directly to the rotor position detector 42 without passing throughthe second controller 50. Also, for example, the rotor position detector42 may be directly coupled to the ground line without passing throughthe second controller 50.

The first controller 20 is a main controller to control driving of themotor 41. The first controller 20 includes the first control circuit 21,a drive circuit 30, and a switch signal detector 23.

The drive circuit 30 is configured to supply a three-phase power to themotor 41 based on a battery power supplied from the battery 15 throughthe second contact of the trigger switch 13. The drive circuit 30includes an inverter. The inverter includes three semiconductorswitching elements Q1 to Q3 as so-called high-side switches, threesemiconductor switching elements Q4 to Q6 as so-called low-sideswitches. Each of the semiconductor switching elements Q1 to Q6 in thepresent embodiment is a Metal Oxide Semiconductor Field-EffectTransistor (MOSFET). A gate signal is inputted from the first controlcircuit 21 to a gate of each of the semiconductor switching elements Q1to Q6. The semiconductor switching elements Q1 to Q6 are each turned ONwhen the gate signal is inputted from the first control circuit 21.

The switch signal detector 23 is configured to detect an ON/Off state ofthe trigger switch 13, that is, an operated/non-operated state of thetrigger operation portion 9. Specifically, the switch signal detector 23is coupled to the second end of the first contact 11 of the triggerswitch 13. When the trigger operation portion 9 is pull-operated tothereby turn ON the first contact 11, a voltage of the battery 15 isinputted to the switch signal detector 23 through the first contact 11.

While the voltage of the battery 15 is inputted, the switch signaldetector 23 outputs a trigger-ON signal Sa indicating that the triggerswitch 13 is ON. The trigger-ON signal Sa outputted from the switchsignal detector 23 is inputted to the first control circuit 21, and isalso inputted to a second control circuit 51 in the second controller50.

The first control circuit 21 includes a one-chip microcomputer,including a CPU 21 a, a memory 21 b, and other components. The memory 21b includes various types of semiconductor memories, such as a RAM, aROM, and a non-volatile memory. The memory 21 b stores various programsand data to be read and executed by the CPU 21 a in order to achievevarious functions of the first controller 20. The programs stored in thememory 21 b include a program of the motor control process in FIG. 3 asdescribed below.

These various functions may be partly or entirely implemented in thefirst control circuit 21 by hardware including a combination of a logiccircuit, an analog circuit, and the like, in place of or in addition tosoftware. Also, the first control circuit 21 including the one-chipmicrocomputer is merely an example, and the first control circuit 21 mayhave various other configurations that allow implementation of thefunctions of the first control circuit 21.

While the trigger-ON signal Sa is not inputted from the switch signaldetector 23, that is, while the trigger switch 13 is OFF, the firstcontrol circuit 21 turns OFF all of the semiconductor switching elementsQ1 to Q6 of the drive circuit 30, to thereby stop the motor 41.

On the other hand, while the trigger-ON signal Sa is inputted from theswitch signal detector 23, the first control circuit 21 rotationallydrives the motor 41. Specifically, the first control circuit 21 detectsthe rotational position of the rotor based on the three positionsignals, that is, the first position signal to the third positionsignal, which are inputted from the rotor position detector 42. Thefirst control circuit 21 performs individual ON/OFF control of thesemiconductor switching elements Q1 to Q6 based on the detectedrotational position, to thereby control an electric current flowing fromthe battery 15 to the motor 41 and rotate the motor 41.

In the present embodiment, the first control circuit 21 is configured torotate the motor 41 in a preset specific rotation direction(hereinafter, the set rotation direction) while the trigger-ON signal Sais inputted.

The electric working machine 1 may include an operation signal outputterthat detects a pull-operation amount of the trigger operation portion 9,and outputs to the first control circuit 2 an operation signalindicating the detected pull-operation amount. In this case, the firstcontrol circuit 21 may be configured to control a rotational speed, arotational torque, or the like of the motor 41 in accordance with thepull-operation amount of the trigger operation portion 9 indicated bythe inputted operation signal.

The electric working machine 1 of the present embodiment is configuredsuch that, while all the Hall sensors in the rotor position detector 42normally operate and the position signals from the Hall sensors arenormally inputted to the first control circuit 21, the three positionsignals to be inputted to the first control circuit 21 will not be at aspecified signal level (for example, an H-level) at the same time. Notethat although all the position signals might be instantaneously at thespecified signal level when respective signal levels of the positionsignals change, such an instantaneous coincidence at the specifiedsignal level is not regarded as “being at the specified signal level atthe same time” here.

The first control circuit 21 is configured not to drive the motor 41 ifa signal abnormal state has occurred in which all the position signalsinputted from the rotor position detector 42 are at the specified signallevel at the same time. That is, if the signal abnormal state hasoccurred, the first control circuit 21 turns OFF all of thesemiconductor switching elements Q1 to Q6 even if the trigger switch 13is ON, to thereby stop electric power supply to the motor 41.Embodiments of the signal abnormal state may include embodiments otherthan the one where all the position signals are at the specified signallevel at the same time.

Also, the first control circuit 21 includes a protection function basedon battery state information inputted from the battery pack 10.Specifically, the first control circuit 21 determines whether anabnormality occurs in the battery 15 based on the battery stateinformation inputted from the battery pack 10. If it is determined thatthe battery 15 is in an abnormal state, the motor 41 is forcibly stoppedeven when the trigger switch 13 is ON.

Further, the first controller 20 includes a power supply controller 22,a current detector 24, a battery voltage detector 25, a boardtemperature detector 26, and an FET temperature detector 27.

The power supply controller 22 receives power supply from the batteryand generates a direct-current control power supply voltage. Componentsin the first controller 20, including the first control circuit 21,operate using the control power supply voltage from the power supplycontroller 22 as a power supply. The control power supply voltagegenerated by the power supply controller 22 is also supplied to thesecond controller 50 as described above.

The current detector 24 is configured to detect an electric currentflowing in the motor 41. The current detector 24 includes, for example,a shunt resistor arranged in a current conduction path from the battery15 to the motor 41, and outputs to the first control circuit 21 avoltage across the shunt resistor as a detection signal indicating acurrent value of the electric current flowing in the motor 41. Thecurrent detector 24 including the shunt resistor is merely an example.The current detector 24 may be configured capable of outputting adetection signal in accordance with the current value of the electriccurrent flowing in the motor 41.

The battery voltage detector 25 is configured to detect a batteryvoltage supplied from the battery 15 of the battery pack 10. The batteryvoltage detector 25, which is coupled to the second end of the firstcontact 11 of the trigger switch 13, outputs to the first controlcircuit 21 a detection signal in accordance with a value of the batteryvoltage inputted through the first contact 11.

The board temperature detector 26 is arranged in a vicinity of the firstcontrol circuit 21 to detect a temperature of the first control circuit21. The board temperature detector 26 includes, for example, athermistor arranged in the vicinity of the first control circuit 21, andoutputs to the first control circuit 21 a detection signal in accordancewith the detected temperature.

The FET temperature detector 27 is arranged in a vicinity of at leastone of the semiconductor switching elements Q1 to Q6 in the drivecircuit 30, in order to detect a temperature of the drive circuit 30.The FET temperature detector 27 includes, for example, a thermistor, andoutputs to the first control circuit 21 a detection signal in accordancewith the detected temperature.

The second controller 50 is an auxiliary controller to detect a rotationdirection of the motor 41, and to conduct or interrupt the three signallines 46 to 48 in accordance with the detection result.

The second controller 50 includes the second control circuit 51. Thesecond control circuit 51 includes a one-chip microcomputer, including aCPU 51 a, a memory 51 b, and other components. The memory 51 b includesvarious semiconductor memories, such as a RAM, a ROM, and a non-volatilememory. The memory 51 b stores various programs and data to be read andexecuted by the CPU 51 a in order to achieve various functions of thesecond controller 50. These various programs include a program for anabnormality monitoring process in FIG. 4 as described below.

These various functions may be partly or entirely implemented, in placeof, or added to, software, by hardware having a combination of a logiccircuit, an analog circuit, and the like in the second control circuit51. Also, the second control circuit 51 including a one-chipmicrocomputer is merely an example, and the second control circuit 51may have various other configurations that allow implementation of thefunctions of the second control circuit 51.

The second controller 50 also includes parts of the three signal lines46 to 48 to transmit three position signals from the rotor positiondetector 42 to the first controller 20, a part of a wiring to supply thecontrol power supply voltage from the first controller 20 to the rotorposition detector 42, and a part of a wiring to couple the rotorposition detector 42 and the ground line.

The second controller 50 of the present embodiment includes a circuitboard. The aforementioned signal lines 46 to 48 and parts of the wiringsare provided on the circuit board. The second control circuit 51 is alsomounted on the circuit board. Providing and/or mounting elements of thesecond controller 50 on the same single circuit board is merely anexample.

As described above, the control power supply voltage generated by thepower supply controller 22 in the first controller 20 is inputted to thesecond controller 50. The components, including the second controlcircuit 51, in the second controller 50 operate by the control powersupply voltage inputted from the first controller 20.

A power supply controller similar to the power supply controller 22 mayalso be provided in the second controller 50, and the second controller50 may operate by the control power supply voltage supplied from thepower supply controller. In such case where the power supply controlleris provided in the second controller 50, the power supply controller maybe configured capable of supplying the control power supply voltage alsoto the first controller 20, and the power supply controller 22 in thefirst controller 20 may be omitted.

The second controller 50 also includes a first interrupter 52, a secondinterrupter 53, and a third interrupter 54. The first interrupter 52 isprovided on the first signal line 46 and configured capable of makingthe first signal line 46 conductive/interrupted. The second interrupter53 is provided on the second signal line 47 and configured capable ofmaking the second signal line 47 conductive/interrupted. The thirdinterrupter 54 is provided on the third signal line 48 and configuredcapable of making the third signal line 48 conductive/interrupted. Theinterrupters 52 to 54 are each controlled by the second control circuit51.

The interrupters 52 to 54 each include a switching element provided on acorresponding signal line. When the switching element is turned ON, thesignal line is made conductive, while when the switching element isturned OFF, the signal line is interrupted.

The switching elements in the interrupters 52 to 54 are each asemiconductor switching element, such as a MOSFET, in the presentembodiment. However, these switching elements may each be one other thana semiconductor switching element, such as a contact relay. Theseswitching elements may each be a so-called normally-open switchingelement, or may each be a so-called normally-closed switching element.

In a normal state, the second control circuit 51 keeps the interrupters52 to 54 ON to make the signal lines 46 to 48 conductive, to therebyinput the position signals from the rotor position detector 42 to thefirst control circuit 21. On the other hand, when an abnormality inrotation direction of the motor 41 is detected, the second controlcircuit 51 turns OFF the interrupters 52 to 54, to thereby interrupt thesignal lines 46 to 48.

A more detailed description will be given of a function of monitoringthe rotation direction of the motor 41 by the second control circuit 51.The second control circuit 51, to which the signal lines 46 to 48 arecoupled, is configured to receive input of the position signals from therotor position detector 42.

While the trigger switch 13 is ON, the second control circuit 51 detectsthe rotation direction of the motor 41 based on the three positionsignals inputted through the signal lines 46 to 48, and determineswhether the detected rotation direction is the set rotation direction.In a case where the detected rotation direction is a reverse directionto the set rotation direction (hereinafter referred to as an “unintendeddirection”), the second control circuit 51 turns OFF all theinterrupters 52 to 54 to interrupt all the signal lines 46 to 48,thereby interrupting input of the three position signals from the rotorposition detector 42 to the first control circuit 21.

The trigger-ON signal Sa from the switch signal detector 23 is inputtedto the second control circuit 51. Thus, the second control circuit 51performs the aforementioned monitoring function while the trigger-ONsignal Sa is inputted.

When the three signal lines 46 to 48 are interrupted, and the positionsignals are no longer inputted to the first control circuit 21, theabove-described signal abnormal state occurs. Thus, when the threesignal lines 46 to 48 are interrupted, and the signal abnormal stateoccurs, the first control circuit 21 stops driving of the motor 41.

That is, while the trigger switch 13 is ON, the second control circuit51 monitors the rotation direction of the motor 41, and stops the motor41 if the motor 41 rotates in the unintended direction. A specificmethod of stopping the motor 41 by the second control circuit 51 in thepresent embodiment is to interrupt the three signal lines 46 to 48 inthe second controller 50 to thereby cause occurrence of the signalabnormal state.

It is merely an example that the second control circuit 51 determinesthe ON/OFF state of the trigger switch 13 based on whether thetrigger-ON signal Sa is inputted. The second control circuit 51 may beable to recognize the ON/OFF state of the trigger switch 13 based on,for example, a signal other than the trigger-ON signal Sa. For example,the trigger switch 13 and the second control circuit 51 may be coupledto each other, thereby allowing the second control circuit 51 to detectwhether the trigger switch 13 is ON not through the first controller 20.

(1-3) Motor Control Process

Next, a description will be given of a motor control process executed bythe first control circuit 21 in the first controller 20 using FIG. 3 .When started, the first control circuit 21 executes the motor controlprocess shown in FIG. 3 .

After starting the motor control process in FIG. 3 , the first controlcircuit 21 determines in S110 whether the trigger switch 13 is ON.Specifically, the determination is made based on whether the trigger-ONsignal Sa is inputted from the switch signal detector 23.

If the trigger switch 13 is OFF, that is, the trigger-ON signal Sa isnot inputted, then a process of stopping the motor 41 is executed inS170, and the process returns to S110. The process executed in S170includes at least a process of turning OFF all of the semiconductorswitching elements Q1 to Q6.

If the trigger switch 13 is ON in S110, that is, the trigger-ON signalSa is inputted, then the process proceeds to S120. In S120, the rotationdirection of the motor 41 is set. In the present embodiment, therotation direction of the motor 41 is previously set to the set rotationdirection. Thus, in S120, the rotation direction of the motor 41 is setto the set rotation direction.

In S130, gate signals are outputted to the drive circuit 30 such thatthe motor 41 rotates in the set rotation direction that has been set inS120. Specifically, to one of the three semiconductor switching elementsQ1 to Q3, as the high-side switches, and to one of the threesemiconductor switching elements Q4 to Q6, as the low-side switches,gate signals to turn ON the two semiconductor switching elements areoutputted, thereby turning ON the two semiconductor switching elements.This causes the motor 41 to rotate in the set rotation direction.

If the gate signals are already outputted in the process of S130, thenthe output of the gate signals is continued.

In S140, a rotor position signal inputted from the signal lines 46 to 48is obtained. The rotor position signal is a collective term for thethree position signals, that is, the first position signal to the thirdposition signal described above.

In S150, it is determined whether an abnormal state has occurred. If anabnormal state has not occurred, then the process proceeds to S160,while if an abnormal state has occurred, then the process proceeds toS170. The abnormal state here includes at least the above-describedsignal abnormal state in the present embodiment. Thus, in the presentembodiment, if the signal abnormal state has occurred, then the processproceeds to S170, in which driving of the motor 41 is stopped.

If an abnormal state has not occurred, then output destinations of thegate signals, that is, semiconductor switching elements to be turned ONare computed in S160 in accordance with the rotor position based on therotor position signal obtained in S140. In a case where the onehigh-side semiconductor switching element and the one low-sidesemiconductor switching element, which are currently ON, should be keptON, the current output destinations of the gate signals are maintained.On the other hand, in a case where it is a time point to change at leastone of the one high-side semiconductor switching element or the onelow-side semiconductor switching element, which is currently ON, toanother semiconductor switching element, the output destination of thegate signal is changed.

Subsequent to the process of S160, the process returns to S110.

(1-4) Abnormality Monitoring Process

Next, a description will be given of an abnormality monitoring processexecuted by the second control circuit 51 in the second controller 50using FIG. 4 . When started, the second control circuit 51 executes theabnormality monitoring process when the trigger switch 13 is turned ON,that is, when the trigger-ON signal Sa is inputted.

When starting the abnormality monitoring process, the second controlcircuit 51 obtains the set rotation direction in S210. The set rotationdirection may be obtainable from the first control circuit 21, or may bepreviously stored, for example, in the memory 51 b in the second controlcircuit 51 and obtained from the memory 51 b.

In S220, the rotor position signal inputted through the signal lines 46to 48 is obtained. In S230, an actual rotation direction of the motor 41is detected based on the rotor position signal obtained in S220, and itis determined whether the actual rotation direction is the same as theset rotation direction. If the actual rotation direction is the same asthe set rotation direction, then the process returns to S210; if theactual rotation direction is the unintended direction, then the processproceeds to S240.

More specifically, the detection of the rotation direction based on therotor position signal is performed in accordance with a changing stateof the rotor position signal obtained in S220. Specifically, in theabnormality monitoring process, obtainment of the rotor position signalin S220 is repeatedly performed as long as a positive determinationcontinues to be made in S230. Also, the rotor position signal obtainedin S220 changes in accordance with changes in the rotational position ofthe motor 41. Thus, in S230, each time the rotor position signalobtained in S220 changes, the rotation direction of the motor 41 isdetected based on the details of the change.

During a period after detecting the rotation direction based on a changein the rotor position signal until a next change in the rotor positionsignal, a state continues where the rotor position signal is constant.During the period, it is regarded in the process of S230 that thecurrently detected rotation direction is maintained.

In S240, an abnormal-time process is executed. Specifically, in thepresent embodiment, the first interrupter 52 to the third interrupter 54are all turned OFF to thereby interrupt the three signal lines 46 to 48.This abnormal-time process leads to occurrence of a signal abnormalstate.

As a result, when the abnormal-time process in S240 is executed, it isdetermined in S150 that an abnormal state has occurred in the motorcontrol process executed by the first control circuit 21 in FIG. 3 , andthereby driving of the motor 41 by the first control circuit 21 isstopped.

The abnormal-time process in S240, that is, interruption of the signallines 46 to 48 by the interrupters 52 to 54, is continued until thetrigger switch 13 is turned OFF. Thus, a user needs to at least bringthe trigger operation portion 9 into a non-operated state to turn OFFthe trigger switch 13, in order to rotate the motor 41 again.

(1-5) Effects of First Embodiment

According to the first embodiment as described above, the second controlcircuit 51 provided separately from the first control circuit 21monitors the rotation direction of the motor 41. If rotation of themotor 41 in the unintended direction is detected, then the secondcontrol circuit 51 executes the abnormal-time process to stop therotation of the motor 41. Specifically, in the first embodiment, inputof the position signals from the rotor position detector 42 to the firstcontrol circuit 21 is interrupted, to thereby stop the motor 41.

Thus, according to the electric working machine 1 of the firstembodiment, in a case where the motor 41 rotates in the unintendeddirection, various influences that might be caused by the rotation inthe unintended direction can be reduced.

Also, the position signals outputted from the rotor position detector 42are not only inputted to the first control circuit 21 to be used forcontrolling the motor 41, but also inputted to the second controlcircuit 51 to be used for detection of the rotation direction of themotor 41 by the second control circuit 51. Accordingly, the positionsignals from the rotor position detector 42 are used efficiently.

In particular, in the first embodiment, the position signals outputtedfrom the rotor position detector 42 are first inputted to the secondcontroller 50, and inputted to the first controller 20 through thesecond controller 50. If the motor 41 rotates in the unintendeddirection, output of the position signals from the second controller 50to the first controller 20 is interrupted. Accordingly, interruption ofthe position signals to the first control circuit 21 by the secondcontrol circuit 51 can be achieved by a simple configuration.

The second control circuit 51 executes the abnormality monitoringprocess while a trigger-ON signal Sa is inputted, that is, while thetrigger switch 13 is ON, and does not execute the abnormality monitoringprocess while the trigger switch 13 is OFF. Accordingly, electric powerconsumption while the trigger switch 13 is OFF can be reduced.

The battery 15 corresponds to one example of a power source in thepresent disclosure. The drive circuit 30 corresponds to one example of adriver in the present disclosure. The process of turning OFF the threeinterrupters 52 to 54 by the second control circuit 51 to corresponds toone example of an abnormality handling process in the presentdisclosure. The power supply controller 22 corresponds to one example ofa power supplier in the present disclosure. The rotor position detector42 corresponds to one example of a position information outputter in thepresent disclosure. The trigger operation portion 9 corresponds to oneexample of an instruction operation device in the present disclosure.The abnormal-time process corresponds to one example of the abnormalityhandling process in the present disclosure. The position signalsoutputted from the respective Hall sensors in the rotor positiondetector 42 correspond to one example of rotational position informationin the present disclosure.

2. Second Embodiment

FIG. 5 shows an electric working machine 70 of a second embodiment.Unlike the first embodiment, the electric working machine 70 of thesecond embodiment is an electric working machine, such as an electricdriver drill and an electric grass cutter, which allows a user toselectively change the rotation direction of the motor to either aforward direction or a reverse direction.

However, the electric working machine 70 of the second embodiment has anelectrical configuration that is mostly the same as that of the firstembodiment; thus, differences will be described below. Referencenumerals identical to those in the first embodiment denote respectiveidentical configurations, and previous description should be referredto.

In a similar manner to the electric working machine 1 of the firstembodiment, the electric working machine 70 of the second embodiment isprovided with the battery pack 10 attachable to and detachable from themain body, and is configured to be operable by the electric power of thebattery 15 in the battery pack 10 attached to the main body. When themotor 41 rotates, its rotational driving force is transmitted through anot-shown transmission mechanism to a working element, thereby drivingthe working element. The working element included in the electricworking machine 70 may be a tool bit in a case where the electricworking machine 70 is, for example, an electric driver drill, or may bea disk-shaped cutting blade having a saw blade along an outer peripherythereof in a case where the electric working machine 70 is, for example,an electric grass cutter.

An electrical configuration of the electric working machine 70 of thesecond embodiment shown in FIG. 5 has mainly three differences below ascompared with the electric working machine 1 of the first embodiment.

The first difference is that a second controller 75 does not includethree signal lines 46 to 48, and no interrupter is provided to the threesignal lines 46 to 48. However, a second control circuit 76 in thesecond controller 75 is coupled to each of the signal lines 46 to 48,and the rotor position signal from the rotor position detector 42 isinputted also to the second control circuit 76.

The second difference is that a forward/reverse selector switch 73 isprovided. The forward/reverse selector switch 73 is a switch to beoperated by a user to selectively change the rotation direction of themotor 41 to either the forward direction or the reverse direction, thatis, to set the rotation direction to either the forward direction or thereverse direction. With respect to the rotation direction of the motor41, it may be determined appropriately which direction should be definedas the forward direction and which direction should be defined as thereverse direction. The forward direction corresponds to one example of afirst direction in the present disclosure, the reverse directioncorresponds to one example of a second direction in the presentdisclosure, and the forward/reverse selector switch 73 corresponds toone example of a direction selecting operation device in the presentdisclosure.

The forward/reverse selector switch 73 outputs a rotation directionsetting signal Sb. The rotation direction setting signal Sb is a signalindicating a state of the forward/reverse selector switch 73, that is, asignal indicating to which of the forward direction and the reversedirection the forward/reverse selector switch 73 is set by a user. Therotation direction setting signal Sb is inputted to a first controlcircuit 72 in a first controller 71 and to the second control circuit 76in the second controller 75.

The third difference is that if detecting that an actual rotationdirection of the motor 41 is the unintended direction, the secondcontrol circuit 76 in the second controller 75 outputs an abnormalitysignal to the first control circuit 72 in the first controller 71. Theset rotation direction in the second embodiment is a rotation directionset by the forward/reverse selector switch 73.

The second control circuit 76 in the second controller 75 executes theabnormality monitoring process when the trigger switch 13 is turned ON,in a similar manner as in the first embodiment. However, in S210, therotation direction indicated by the rotation direction setting signal Sbinputted from the forward/reverse selector switch 73 is obtained as theset rotation direction. Also, the abnormal-time process in S240 includesa notification process of providing a specific notification to the firstcontrol circuit 72. Specifically, in the notification process, anabnormality signal is outputted to the first control circuit 72. Theprocesses in S220 and S230 are the same as those in the firstembodiment.

When started, the first control circuit 72 in the first controller 71executes the motor control process in FIG. 3 in a similar manner as inthe first embodiment. However, in S120, a rotation direction indicatedby the rotation direction setting signal Sb inputted from theforward/reverse selector switch 73 is set as the set rotation direction.Also, in the second embodiment, the abnormal state in S150 includes atleast input of an abnormality signal from the second control circuit 76.Thus, in the second embodiment, if an abnormality signal is inputtedfrom the second control circuit 76, then the process proceeds to S170,and driving of the motor 41 is stopped.

The abnormality signal outputted from the second control circuit 76 maybe any type of signal. The abnormality signal may be, for example, a1-bit or multi-bit digital signal. The abnormality signal may also be,for example, an analog signal. The specific notification to the firstcontrol circuit 72 may be performed in a manner different fromoutputting an abnormality signal. For example, in a case where the firstcontrol circuit 72 is provided with a reset signal input terminal toreset the CPU included in the first control circuit 72, the specificnotification may be inputting a reset signal to the reset signal inputterminal. When a reset signal is inputted to the first control circuit72, the CPU is reset, and gate signals are all turned OFF; as a result,the motor 41 is stopped.

According to the second embodiment as described above, if rotation ofthe motor 41 in the unintended direction is detected, the second controlcircuit 76 executes an abnormality handling process. Specifically, anabnormality signal is outputted to the first control circuit 72. Whenthe abnormality signal is inputted from the second control circuit 76,the first control circuit 72 stops the motor 41.

Accordingly, if the motor 41 rotates in the unintended direction, themotor 41 can be stopped by a simple process of outputting an abnormalitysignal to the first control circuit 72.

Also, regardless of whether the rotation direction is set to the forwarddirection or set to the reverse direction by the forward/reverseselector switch 73, the motor 41 can be stopped if rotation in theunintended direction is detected.

3. Third Embodiment

FIG. 6 shows an electric working machine 80 of a third embodiment. Sincethe electric working machine 80 of the third embodiment has a basicconfiguration similar to that in the first embodiment, differences willbe described below. Reference numerals identical to those in the firstembodiment denote respective identical configurations, and previousdescription should be referred to.

Compared with the electric working machine 1 of the first embodiment,the electric working machine 80 of the third embodiment has mainly twodifferences below.

The first difference is that a rotor position detector 83 is provided ina first controller 81, includes no Hall sensor, and is configured togenerate a position detection signal for each phase based on a voltagevalue of a wiring of the phase for supplying three-phase power from thedrive circuit 30 to the motor 41.

The second difference is that a second controller 85 is provided in thefirst controller 81. Specifically, in the first embodiment and thesecond embodiment, the first controller and the second controller areconfigured as separate controllers each having a circuit board, on whichwiring and components are mounted. In contrast, in the third embodiment,the first controller 81 and the second controller 85 are mounted on thesame single circuit board.

The rotor position detector 83 obtains the voltage values of the wiringsof respective phases to supply three-phase power from the drive circuit30 to the motor 41. The rotor position detector 83 performs a specifiedsignal processing for each phase based on the obtained voltage value,and outputs a position detection signal. Then, the first control circuit21 detects the rotational position of the motor 41 based on the positiondetection signals of the respective phases from the rotor positiondetector 83.

A specific method for generating position detection signals of therespective phases based on the obtained voltage values of the respectivephases in the rotor position detector 83, and a specific method fordetecting the rotation direction based on the position detection signalsof the respective phases in the first control circuit 21 may be commonlyused methods in a so-called sensor-less control of a brushless motor.

The position detection signals of the respective phases outputted fromthe rotor position detector 83 are inputted to the first control circuit21 through the respective signal lines.

The second controller 85 has basically the same configuration as thesecond controller 50 of the first embodiment. Specifically, the secondcontroller 85 includes parts of the three signal lines to transmitposition detection signals of the respective phases from the rotorposition detector 83 to the first control circuit 21. Similarly to thefirst embodiment, the first interrupter 52, the second interrupter 53,and the third interrupter 54 are provided to the respective signallines.

A second control circuit 86 detects the rotation direction of the motor41 based on the position detection signals of the respective phasesoutputted from the rotor position detector 83. If the detected directionis the unintended direction, the second control circuit 86 turns OFF theinterrupters 52 to 54 to thereby interrupt input of the positiondetection signals to the first control circuit 21, similarly to thefirst embodiment. When inputs of the position detection signals areinterrupted, a signal abnormal state occurs, and thus the first controlcircuit 21 stops the motor 41.

The second control circuit 86 in the second controller 85 executes theabnormality monitoring process when the trigger switch 13 is turned ON,in a similar manner as in the first embodiment. However, the rotorposition signal obtained in S220 is the position detection signals inthe respective three phases inputted from the rotor position detector83.

In the electric working machine 80 of the third embodiment as describedabove, the sensor-less control using no sensing element, such as a Hallsensor, is employed for detection of the rotational position of themotor 41. The electric working machine 80 with such configuration alsocan achieve similar effects and operations as those in the firstembodiment.

4. Fourth Embodiment

FIG. 7 shows an electric working machine 100 of a fourth embodiment.Since the electric working machine 100 of the fourth embodiment has abasic configuration similar to that in the first embodiment, differenceswill be described below. Reference numerals identical to those in thefirst embodiment denote respective identical configurations, andprevious description should be referred to.

Compared with the electric working machine 1 of the first embodiment,the electric working machine 100 of the fourth embodiment has mainlyfive differences below.

The first difference is that a second controller 110 does not includethe interrupters 52 to 54 to interrupt the signal lines 46 to 48.

The second difference is that, a control power supply interrupter 103 tointerrupt a power supply wiring 113, which supplies the control powersupply voltage from the power supply controller 22 to a first controlcircuit 102, is provided on the power supply wiring 113, among theplurality of electric wirings arranged in the electric working machine100.

The third difference is that a gate signal interrupter 104 to interruptgate signal wirings 114, which output gate signals from the firstcontrol circuit 102 to the semiconductor switching elements Q1 to Q6, isprovided on the gate signal wirings 114, among a plurality of electricwirings arranged in the electric working machine 100. The gate signalwirings 114 correspond to one example of a control wiring in the presentdisclosure, and the gate signal corresponds to one example of a controlsignal in the present disclosure.

The fourth difference is that a drive power supply interrupter 105 tointerrupt a drive wiring 115, which supplies a battery voltage from thebattery 15 through the second contact 12 to the drive circuit 30, isprovided on the drive wiring 115, among the plurality of electricwirings arranged in the electric working machine 100.

The fifth difference is that, in a case where the motor 41 rotates inthe unintended direction, a second control circuit 111 in the secondcontroller 110 turns OFF at least one of the control power supplyinterrupter 103, the gate signal interrupter 104, or the drive powersupply interrupter 105, to thereby interrupt the wiring with the turnedOFF interrupter.

For example, if the control power supply interrupter 103 is turned OFF,and thus the power supply wiring 113 is interrupted, the control powersupply voltage is not inputted to the first control circuit 102, therebybringing the first control circuit 102 into a non-operating state. As aresult, all the semiconductor switching elements Q1 to Q6 in the drivecircuit 30 are turned OFF, and the motor 41 is stopped.

Also, for example, if the gate signal interrupter 104 is turned OFF, andthus the gate signal wiring 114 is interrupted, all the semiconductorswitching elements Q1 to Q6 in the drive circuit 30 are turned OFF, andthe motor 41 is stopped.

Further, for example, if the drive power supply interrupter 105 isturned OFF, and thus the drive wiring 115 is interrupted, electric powerfrom the battery is not supplied to the motor 41 regardless of whetheror not the semiconductor switching elements Q1 to Q6 are ON, and thusthe motor 41 is stopped.

In other words, if at least one of the control power supply interrupter103, the gate signal interrupter 104, or the drive power supplyinterrupter 105 is turned OFF, the motor 41 is stopped. The controlpower supply interrupter 103, the gate signal interrupter 104, and thedrive power supply interrupter 105 each correspond to one example of aninterrupter in the present disclosure.

The control power supply interrupter 103 includes, for example, anMOSFET, inserted in the power supply wiring 113, and the MOSFET isconfigured to be turned ON/OFF by the second control circuit 111. It maybe configured such that the power supply wiring 113 is interrupted whenthe MOSFET is turned ON, and the power supply wiring 113 is brought intoconduction when the MOSFET is turned OFF. Also, the control power supplyinterrupter 103 is configured to be OFF while the control power supplyvoltage is not generated by the power supply controller 22, and to be ONwhile the control power supply voltage is generated.

The control power supply interrupter 103 may be configured not to be ONonly because the control power supply voltage is generated, but to be ONwhile the trigger switch 13 is further ON. The control power supplyinterrupter 103 may also include a so-called normally-closed switch thatis normally kept ON regardless of whether or not the control powersupply voltage is generated. Alternatively, the control power supplyinterrupter 103 may include a so-called normally-open switch that isnormally kept OFF.

The gate signal interrupter 104 and the drive power supply interrupter105 also each include, for example, a semiconductor switching element,such as an MOSFET inserted in interruption target wirings. When started,the first control circuit 102 normally turns ON the interrupters 104,105 to bring the respective interruption target wirings into conduction.

In the operation of the gate signal interrupter 104 and the drive powersupply interrupter 105, control by the second control circuit 111 isprioritized over control by the first control circuit 102. Thus, evenwhen the first control circuit 102 controls the gate signal interrupter104 and the drive power supply interrupter to be ON, if the secondcontrol circuit 111 controls the gate signal interrupter 104 and thedrive power supply interrupter 105 to be OFF, the control by the secondcontrol circuit 111 is prioritized, and thereby the gate signalinterrupter 104 and the drive power supply interrupter 105 are turnedOFF.

The gate signal interrupter 104 and the drive power supply interrupter105 each may include a so-called normally-closed switch that is normallykept ON. In this case, the control of the gate signal interrupter 104and the drive power supply interrupter 105 by the first control circuit102 is unnecessary.

When the trigger switch 13 is turned ON, the second control circuit 111in the second controller 110 executes the abnormality monitoringprocess, similarly to the first embodiment. However, in S240, a processof turning OFF at least one of the control power supply interrupter 103,the gate signal interrupter 104, or the drive power supply interrupter105 is executed as an abnormal-time process. In the abnormal-timeprocess, any one of the three interrupters 103 to 105 may be turned OFF.Also, two of the three interrupters 103 to 105 may be turned OFF, or allof these may be turned OFF.

When started, the first control circuit 102 in the first controller 101executes a motor control process in FIG. 8 . After starting the motorcontrol process in FIG. 8 , the first control circuit 102 determines inS310 whether the trigger switch 13 is ON, in the same manner as in S110of FIG. 3 . If the trigger switch 13 is OFF, then a process of stoppingthe motor 41 is executed in S370, and the process returns to S310.

If the trigger switch 13 is ON, then the process proceeds to S320. InS320, the gate signal interrupter 104 and the drive power supplyinterrupter 105 are turned ON, to thereby bring the two interruptiontarget wirings into conduction.

Processes in S330, S340, S350, and S360 are respectively the same as theprocesses in S120, S130, S140, and S160 in FIG. 3 .

According to the fourth embodiment as described above, if the motor 41rotates in the unintended direction, the motor 41 can be stopped byturning OFF at least one of the three interrupters 103 to 105.

Particularly, in the fourth embodiment, the motor 41 is stopped notthrough the control by the first control circuit 102 but throughinterruption of a specific electric wiring. If the power supply wiring113, the gate signal wiring 114, or the drive wiring 115 is interrupted,electric conduction to the motor 41 is stopped regardless of theoperation state of the first control circuit 102, and the motor 41 isstopped. Accordingly, even if the CPU in the first control circuit 102runs out of control to be in an abnormal state where the drive circuit30 cannot be controlled normally when rotation in the unintendeddirection is detected, the motor 41 can be stopped.

5. Other Embodiments

Although some embodiments of the present disclosure have been describedabove, the present disclosure is not limited to the above-describedembodiments, but may be practiced with various modifications.

(5-1) In the first embodiment, the three interrupters 52 to 54 in thesecond controller 50 may be provided outside the second controller 50.In other words, the interrupters 52 to 54 may be provided anywhere inthe corresponding signal lines 46 to 48 from the rotor position detector42 to the first control circuit 21.

Alternatively, an interrupter may be provided in a supply path of thecontrol power supply voltage from the first controller 20 to the rotorposition detector 42. In this case, the second control circuit 51 mayturn ON the interrupter in the supply path of the control power supplyvoltage, as the abnormal-time process, to interrupt supply of thecontrol power supply voltage to the rotor position detector 42, therebycausing the signal abnormal state.

(5-2) The trigger switch 13 may have a single contact instead of the twocontacts, or may have three or more contacts. That is, the triggerswitch 13 may supply the battery voltage to the first controller 20through a single current path or three or more current paths.

(5-3) The power supply controller 22 may receive input of informationindicating ON/OFF of the trigger switch 13, and may generate the controlpower supply voltage in accordance with the ON/OFF of the trigger switch13. For example, the power supply controller 22 may generate the controlpower supply voltage while the trigger switch 13 is ON, and stopgenerating the control power supply voltage while the trigger switch 13is OFF.

The trigger switch 13 may be arranged in the current conduction paththat couples the battery 15 and the power supply controller 22, to allowthe battery voltage to be supplied to the power supply controller 22while the trigger switch 13 is ON.

(5-4) Also, in the first embodiment, the second embodiment, and thefourth embodiment, the first controller 81 and the second controller 85may be mounted on the same single circuit board similarly to the thirdembodiment. That is, elements of the two controllers, including thefirst control circuit and the second control circuit, may be mounted onthe same single circuit board.

(5-5) The rotor position detector 42 shown in the first embodiment, thesecond embodiment, and the fourth embodiment, as well as the rotorposition detector 83 shown in the third embodiment are merely examplesof a position information detector to detect the rotational position ofthe motor 41. The position information detector may be configured todetect the rotational position of the motor 41 using, for example, adetection device other than a Hall sensor.

(5-6) The motor 41 may be a motor other than a brushless motor. Thedrive circuit 30 shown, for example, in FIG. 1 is merely an example of adriver to conduct current to the motor 41. Drivers having differentconfigurations depending on types of the motor 41 may be employed.

For example, a brushed DC motor may be used for the motor 41, and anH-bridge circuit with four semiconductor switching elements may be usedfor the driver. Also, for example, the driver may include onesemiconductor switching element provided in the current conduction pathfrom the power source to the motor.

(5-7) The battery pack attachable to and detachable from the main bodyis merely an example. For example, a battery may be installed in themain body.

Also, a motor drive power source is not limited to the battery 15, butmay be another power source. For example, alternating current power maybe inputted from an external commercial power source, or the like, todrive the motor based on the alternating current power. In this case,the inputted alternating current power may be supplied directly to themotor, or the alternating current power may be converted by a converterinto direct current power, and the converted direct current power may besupplied to the motor. Alternatively, the converted direct current poweris further converted into alternating current power by an inverter, orthe like, to be supplied to the motor.

(5-8) The circular saw of the first embodiment, and the electric driverdrill or the electric grass cutter of the second embodiment are merelyexamples of an electric working machine to which the present disclosureis applicable. The present disclosure may be applied not only to thecircular saw, the electric driver drill, and the electric grass cutter,but also to various electric working machines, such as electric powertools for gardening, masonry work, metalworking, and woodworking. Morespecifically, the present disclosure may be applied to various electricworking machines, such as an electric hammer, an electric hammer drill,an electric drill, an electric driver, an electric wrench, an electricgrinder, an electric reciprocating saw, an electric jigsaw, an electriccutter, an electric chainsaw, an electric planer, an electric nail gun(including a tacker), an electric hedge trimmer, an electric lawn mower,an electric lawn trimmer, an electric cleaner, an electric blower, anelectric sprayer, an electric spreader, and an electric dust collector.

(5-9) A plurality of functions achieved by a single element in theaforementioned embodiments may be achieved by a plurality of elements,or a function achieved by a single element may be achieved by aplurality of elements. Also, a plurality of functions achieved by aplurality of elements may be achieved by a single element, or a functionachieved by a plurality of elements may be achieved by a single element.Further, a part of a configuration in the aforementioned embodiments maybe omitted.

Moreover, at least a part of an element included in one of theaforementioned embodiments may be added to, or may replace, another oneof the aforementioned embodiments. For example, in a case where theelectric working machine 1 of the first embodiment is configured as anelectric working machine, such as an electric driver drill or anelectric grass cutter, in which the rotation direction of the motor isselectively changeable between a forward direction and a reversedirection, the electric working machine 1 may include theforward/reverse selector switch 73 shown in the second embodiment.Further, for example, the second embodiment and the third embodiment mayemploy at least one of the three interrupters 103, 104, 105 shown in thefourth embodiment.

The invention claimed is:
 1. An electric working machine comprising: atrigger switch; a saw blade; a motor operably connected to the saw bladeso as to drive the saw blade; a drive circuit operably connected to themotor, to the trigger switch, and to a battery so as to drive the motorby electric power supplied from the battery in response to turning ON ofthe trigger switch; a rotor position detector configured to detect arotor position of the motor and configured to output a first positionsignal; a first control circuit configured to receive the first positionsignal, the first control circuit being operably connected to the drivecircuit so as to control the drive circuit such that the motor rotatesin a set rotation direction, the first control circuit being configuredto control the drive circuit based on the first position signal tothereby rotate the motor in the set rotation direction; a first signalline that connects the rotor position detector to the first controlcircuit, the first signal line being configured to receive the firstposition signal from the rotor position detector, the first signal linebeing configured to output, to the first control circuit, the firstposition signal received from the rotor position detector; and a secondcontrol circuit having an input connected to the first signal line andhaving an output connected to one of the first control circuit or thefirst signal line, the second control circuit being configured toreceive the first position signal from the first signal line, the secondcontrol circuit being configured to detect a rotation direction of themotor based on the first position signal received from the first signalline, and the second control circuit being configured to perform anabnormality handling process and provide an output signal via the outputto the one of the first control circuit or the first signal line to stoprotation of the motor in response to a situation where the rotationdirection detected by the second control circuit is reverse to the setrotation direction.
 2. The electric working machine according to claim1, further comprising: a trigger operation portion operably connected tothe trigger switch and configured to be operated by an operator of theelectric working machine to rotate the motor, wherein the first controlcircuit and the second control circuit are operably connected to thetrigger operation portion via the trigger switch and configured so as tooperate in response to an operation of the trigger operation portion. 3.An electric working machine comprising: a motor; a drive circuitoperably connected to a power source and to the motor so as to drive themotor; a rotor position detector configured to detect a rotor positionof the motor and configured to output a first position signal; a firstcontrol circuit configured to receive the first position signal, thefirst control circuit being operably connected to the drive circuit soas to control the drive circuit such that the motor rotates in a setrotation direction, the first control circuit being configured tocontrol the drive circuit based on the first position signal to therebyrotate the motor in the set rotation direction; a first signal line thatconnects the rotor position detector to the first control circuit, thefirst signal line being configured to receive the first position signalfrom the rotor position detector, the first signal line being configuredto output, to the first control circuit, the first position signalreceived from the rotor position detector; and a second control circuithaving an input connected to the first signal line and having an outputconnected to one of the first control circuit or the first signal line,the second control circuit being configured to receive the firstposition signal from the first signal line, the second control circuitbeing configured to detect a rotation direction of the motor based onthe first position signal received from the first signal line, and thesecond control circuit being configured to perform an abnormalityhandling process and provide an output signal via the output to the oneof the first control circuit or the first signal line to stop rotationof the motor in response to a situation where the detected rotationdirection is reverse to the set rotation direction.
 4. The electricworking machine according to claim 3, wherein the output of the secondcontrol circuit is connected to the first control circuit, and theabnormality handling process includes a notification process ofproviding a specific notification to the first control circuit, andwherein the first control circuit is configured to stop rotation of themotor through the drive circuit in response to execution of thenotification process.
 5. The electric working machine according to claim3, comprising: a first controller including the first control circuit;and a second controller including the second control circuit and a partof the first signal line, wherein the input of the second controlcircuit is connected to the part of the first signal line and the outputis connected to the part of the first signal line, wherein the firstcontrol circuit is configured to stop driving of the motor by the drivecircuit in response to stopping of input of the first position signalfrom the first signal line, and wherein the abnormality handling processincludes a process of allowing input of the first position signal fromthe first signal line to the second control circuit, while blockinginput of the first position signal from the first signal line to thefirst control circuit.
 6. The electric working machine according toclaim 3, further comprising: a direction selecting operation deviceoperably connected to the first control circuit and the second controlcircuit and configured to be operated to set the rotation direction ofthe motor to a first direction or a second direction, wherein the setrotation direction corresponds to the rotation direction set by thedirection selecting operation device.
 7. An electric working machinecomprising: a motor; a drive circuit operably connected to a powersource and to the motor so as to drive the motor; a rotor positiondetector configured to detect a rotor position of the motor andconfigured to output a first position signal; a first controllerincluding the drive circuit and a first control circuit, the firstcontrol circuit being connected to the rotor position detector via afirst signal line so as to receive the first position signal, the firstcontrol circuit being operably connected to the drive circuit so as tocontrol the drive circuit, the first control circuit being configured tocontrol the drive circuit based on the first position signal to therebyrotate the motor in a set rotation direction, the first control circuitbeing configured to stop driving of the motor by the drive circuit inresponse to termination of reception of the first position signal by thefirst control circuit; and a second controller including a secondcontrol circuit and a part of the first signal line, the second controlcircuit being connected to the first signal line so as to receive thefirst position signal and configured to provide an output to the part ofthe first signal line, the second control circuit being programmed toperform: a first function of detecting a rotation direction of the motorbased on the first position signal, and a second function of terminatingoutput of the first position signal from the second controller to thefirst controller to thereby stop rotation of the motor, in response to asituation where the rotation direction detected by the first function isreverse to the set rotation direction.